What are your intentions with defence scaling?
defence should be universal for all samurai and especially bushi. Not something hidden in special techniques. That +1 flat value from a stance doesn't scale.
As you grow more competent at attacking, your defence should follow the same increase to maintain balance. Otherwise we'll see new samurai missing a lot and seasoned but equal opponents never missing. Wfrp has the same issue.
With the current rules the only option is to allow defence checks so attacking is competitive, and both parties Pick Their dice in secret at then reveal, to keep some choice in the system akin to raises.
Defence... really it is a fundamental part of combat.
Edited by Gallows